How do I subdivide smooth in blender 2.8?
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It appears that they have removed the Subdivide Smooth option in 2.80 (at least  in the version I have). However, it's always actually been a bit redundant as the Subdivide tool has a Smoothness slider that, when set to 1, behaves the exact same way as Subdivide smooth did. Plus, Blender will use your most recently used settings when subdividing, so it will the Subdivide tool will act exactly like Subdivide Smooth until you tell it otherwise (or close Blender). The Subdivide tool should still be in the specials menu like before.